If it seems as though the first five seasons of "Mad Men" were often about trying to understand Don Draper's past, it isn't too much of a leap to think that we could focus more on his future and that of other characters as the show begins its penultimate season on Sunday night, April 7.

Some viewers felt the fifth season wasn't one of the AMC series' best, and, to be sure, there was a sense that Draper and his advertising agency were becalmed in confusion about how to adapt to changing times in the middle of the turbulent '60s.

But those who've followed the show have already learned that it is only episodic in the way chapters of a great novel contribute to the full story.

As usual, creator Matthew Weiner asks that critics not include spoilers about the premiere in our reviews. We're not supposed to tell you what year it is, for example, although it's not overtly stated in the premiere anyway. Nor are we to tell you the status of the relationship between Don (Jon Hamm) and Megan (Jessica Pare) and whether Sterling Cooper has expanded to an additional floor.

After five years of sifting and re-sifting through real and false clues in "Mad Men," even these seemingly irrelevant advisories send us off on a mental scavenger hunt even before the premiere episode's first scene, which shows Don reading on a sunny beach.

The suggestion that we are beginning a two-season process of summing up is underscored by the title of Sunday's double episode, "The Doorway." We hear the word "doorway" and we think "entrance."

But doorways go both ways -- you can enter through one, but you can also leave through one. And what if you open a door and there is nothing there -- literally nothing? No floor, no other room, nothing to keep you from tumbling to your doom, perhaps like the silhouetted figure in the opening credits of "Mad Men."

The season-opener is littered with references to mortality, some of them humorous, others more ponderous. Knowing Don's past, that he is a literal version of the American ideal of the self-made man, who appropriated his identity from a dead soldier in Korea, how does mortality come into play here?

Is Weiner suggesting or teasing us that Don or other major characters may die? Or could he be setting us up for the death of the appropriated identity of Don?

Throughout the opener, casual remarks pop out from the chatter. We wouldn't give most of them a second thought in real life or in any other TV show, but Weiner has conditioned us to listen more closely when they are spoken by a "Mad Men" character.

One reason some viewers found the fifth season disappointing was that despite being married now (or perhaps because of it, in part), Don has been growing more and more ill at ease, more haunted. His darkening ennui suggests that his purloined identity may be chafing more than before: He has never been comfortable in his own skin because that "skin" isn't his own.

In Sunday's episode, we hear a photographer say to Don, "I want you to be yourself," during a photo shoot of Sterling Cooper's major players. The irony of that request isn't lost on us, but we can't help feeling that it must be obvious to Don at that moment as well.

Whatever will happen in the finale of "Mad Men" in the seventh season, Don Draper's journey has been and remains maddening, in a very good way as far as what makes a great TV show.

The show is, of course, already a classic because of great writing, direction, performances and design, but also because Weiner has consistently nurtured it as a piece of literature. In so doing, he has more than proved that television has the potential to delve as deeply into character as a great novel often does.

Our occasional disappointment may derive from how we've been conditioned to view a TV series. With an equally good show like "Breaking Bad," for example, the audience gets a lot of edginess and action along with the metaphysical explorations of good and evil by creator Vince Gilligan. Meth labs, though, offer more opportunities for action than advertising agencies.

The action of "Mad Men" is largely psychological, and much involves Don wrestling with himself. We want to root for him, of course, and that's one of the things that hold our interest from season to season.

At the same time, we are never sure who we're really rooting for. If that frustrates, and it inevitably will, stick around. There's a reason for almost everything in "Mad Men."

By the way, the book in Don's hands on that sunny beach in the opening scene is "The Inferno," Dante's poetic meditation on hell. Probably just a coincidence, right?